The present invention relates to a device for regulating the speed of a motor vehicle provided with a braking device, comprising a control actuatable by the driver of the vehicle, with first means for setting a command value for a speed, a sensor for sensing the actual value of the speed and a processing unit connected to the engine throttle and to the braking device, said command value and actual value being fed into and compared in said processing unit, which is disposed to send signals to the throttle and/or brake device depending on the difference between said values, said processing unit being disposed when driving downhill to allow a maximum speed, which lies above the command value set by means of the first means.